According toThe West Australian, Mr Djurasovic found one of his daughters on the floor near the entrance to the home and the other in the laundry.

"His face was just white. He couldn't talk. His face was in shock," an unnamed neighbour told the paper.

Another neighbour, Gordana Sousak said she heard screaming at about 6pm after Mr Djurasovic returned home from work.

"When he called police they told him not to touch her, but by that time he'd found the other little girl in the laundry," she told WA Today.

Police have devastated the community. Picture: Sec

In a moving tribute posted to Facebook overnight, Mr Couper described the agony of having to break the news about Mia's death to his daughter.

"Tonight Terri and I had to do something that as parents, we never ever thought we'd have to do," he wrote.

"That is explain to our 10 year old daughter Mia how her best friend, Mia Djurasovic was one of the two children (who died) in Madeley.

"When we heard about the (deaths) yesterday we were both distressed and our hearts broke for the two children involved …

"Our daughter Mia went to a birthday party for another school friend this afternoon and heard the parents talking about Mia D. Earlier tonight, The West Australian released the names and our world changed forever as when our Mia come home tonight and told us about Mia D, and we saw the West Australian article, suffice to say we were all in shock.

"Our family is close to the Djurasovic family as our Mia, Mia D and her sister Tiana D (6) we're close and they only played together at school a few days ago. The sisters were inseparable and only a few months ago, Mia D attended our Mia's 10th birthday party, and the photos are a surreal moment in time as all the kids were so happy and Terri and I were talking to all the parents including Mum Milka.

"Our daughter is very distraught and upset that neither Mia D or Tiana D will be at school on Monday and neither will she get her daily hug from Mia D who was like a big sister to all the girls. Understandably our Mia is asking why, and questions Terri and I never thought we would have to answer.

"Premier Mark McGowan tonight advised that the school will have psychological support and councillors on Monday. Mark, these two young girls were so cherished and the family respected that many are now struggling to understand why themselves so the offer of psychological support is appreciated as Terri and I both know our Mia will need this support.

"Finally, to Mia and Tiana D, we sincerely pray and hope that the Lord has you both in his arms, that you are not suffering anymore and most importantly know how much you are loved and will be sadly missed. Mia has asked me to let you know that she loves you and misses you both so very much.

"To Milka, Nenad, grandparents and Mia and Tiana's extended family and friends, we are so very sorry and our thoughts and prayers are with you all during this time.

"How do you put all this in perspective I sincerely ask. Parents should not outlive our children and Terri and I never expected to be impacted as we have by these senseless (deaths), and the loss of two very beautiful young girls.

RIP beautiful Mia & Tiana D."

Part of Bogdanich Way remains cordoned off today as police continued their investigations.

An evidence collection station has been established at the house, which is in a new residential estate.

Commissioner Steel said forensic officers and homicide investigators would work "meticulously" at the crime scene in coming weeks.

"I can assure the people of Western Australia, that the WA police are doing all that they can to investigate this matter and try and identify what it is that led to these tragic events," he said.

"Our homicide squad are undertaking a thorough and professional investigation and our highly trained forensic officers are working meticulously through the crime scene to try and identify information which will help us understand what led to these events."